Multi-layer micro-wire substrate structure

ABSTRACT

A multi-layer micro-wire structure includes a substrate having a substrate edge. A first layer is formed over the substrate extending to a first layer edge. One or more first micro-channels are imprinted in the first layer, at least one imprinted first micro-channel having a micro-wire forming at least a portion of an exposed first connection pad in the first layer. A second layer is formed over the first layer extending to a second layer edge. One or more second micro-channels are imprinted in the second layer, at least one imprinted second micro-channel having a micro-wire forming at least a portion of an exposed second connection pad in the second layer. The second-layer edge is farther from the substrate edge than the first-layer edge for at least a portion of the second-layer edge so that the first connection pads are exposed through the second layer.

CROSS REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly-assigned, co-pending U.S. patentapplication Ser. No. ______ (Kodak Docket K001549) filed concurrentlyherewith, entitled “Multi-Layer Micro-Wire Substrate Method” by RonaldS. Cok, the disclosure of which is incorporated herein.

FIELD OF THE INVENTION

The present invention relates to substrates having imprinted micro-wiresformed in multiple layers.

BACKGROUND OF THE INVENTION

Transparent conductors are widely used in the flat-panel displayindustry to form electrodes that are used to electrically switchlight-emitting or light-transmitting properties of a display pixel, forexample in liquid crystal or organic light-emitting diode displays.Transparent conductive electrodes are also used in touch screens inconjunction with displays. In such applications, the transparency andconductivity of the transparent electrodes are important attributes. Ingeneral, it is desired that transparent conductors have a hightransparency (for example, greater than 90% in the visible spectrum) anda low electrical resistivity (for example, less than 10 ohms/square).

Transparent conductive metal oxides are well known in the display andtouch-screen industries and have a number of disadvantages, includinglimited transparency and conductivity and a tendency to crack undermechanical or environmental stress. Typical prior-art conductiveelectrode materials include conductive metal oxides such as indium tinoxide (ITO) or very thin layers of metal, for example silver or aluminumor metal alloys including silver or aluminum. These materials arecoated, for example, by sputtering or vapor deposition, and arepatterned on display or touch-screen substrates, such as glass.

Transparent conductive metal oxides are increasingly expensive andrelatively costly to deposit and pattern. Moreover, the substratematerials are limited by the electrode material deposition process (e.g.sputtering) and the current-carrying capacity of such electrodes islimited, thereby limiting the amount of power that is supplied to thepixel elements. Although thicker layers of metal oxides or metalsincrease conductivity, they also reduce the transparency of theelectrodes.

Transparent electrodes, including very fine patterns of conductiveelements, such as metal wires or conductive traces are known. Forexample, U.S. Patent Publication No. 2011/0007011 teaches a capacitivetouch screen with a mesh electrode, as do U.S. Patent Publication No.2010/0026664, U.S. Patent Publication No. 2010/0328248, and U.S. PatentNo. 8,179,381, which are hereby incorporated in their entirety byreference. As disclosed in U.S. Pat. No. 8,179,381, fine conductorpatterns are made by one of several processes, including laser-curedmasking, inkjet printing, gravure printing, micro-replication, andmicro-contact printing. In particular, micro-replication is used to formmicro-conductors formed in micro-replicated channels. The transparentmicro-wire electrodes include micro-wires between 0.5 μ and 4 μ wide anda transparency of between approximately 86% and 96%.

Conductive micro-wires are formed in micro-channels embossed in asubstrate, for example as taught in CN102063951, which is herebyincorporated by reference in its entirety. As discussed in CN102063951,a pattern of micro-channels are formed in a substrate using an embossingtechnique. Embossing methods are generally known in the prior art andtypically include coating a curable liquid, such as a polymer, onto arigid substrate. A pattern of micro-channels is embossed (impressed orimprinted) onto the polymer layer by a master having an inverted patternof structures formed on its surface. The polymer is then cured. Aconductive ink is coated over the substrate and into the micro-channels,the excess conductive ink between micro-channels is removed, for exampleby mechanical buffing, patterned chemical electrolysis, or patternedchemical corrosion. The conductive ink in the micro-channels is cured,for example by heating. In an alternative method described inCN102063951, a photosensitive layer, chemical plating, or sputtering isused to pattern conductors, for example using patterned radiationexposure or physical masks. Unwanted material (e.g. photosensitiveresist) is removed, followed by electro-deposition of metallic ions in abath.

Referring to FIG. 16, a prior-art display and touch-screen system 100includes a display 110 with a corresponding touch screen 120 mountedwith the display 110 so that information displayed on the display 110 isviewed through the touch screen 120. Graphic elements displayed on thedisplay 110 are selected, indicated, or manipulated by touching acorresponding location on the touch screen 120. The touch screen 120includes a first transparent substrate 122 with first transparentelectrodes 130 formed in the x-dimension on the first transparentsubstrate 122 and a second transparent substrate 126 with secondtransparent electrodes 132 formed in the y-dimension facing thex-dimension first transparent electrodes 130 on the second transparentsubstrate 126. A dielectric layer 124 is located between the first andsecond transparent substrates 122, 126 and first and second transparentelectrodes 130, 132. The first and second transparent substrates 122,126, and dielectric layer 124 are formed separately and laminatedtogether.

The first and second transparent electrodes 130, 132 have a variablewidth and extend in orthogonal directions (for example as shown in U.S.Patent Application Publication Nos. 2011/0289771 and 2011/0099805). Whena voltage is applied across the first and second transparent electrodes130, 132, electric fields are formed between the first pad areas 128 ofthe x-dimension first transparent electrodes 130 and the second padareas 129 of the y-dimension second transparent electrodes 132.

A display controller 142 connected through electrical buss connections136 controls the display 110 in cooperation with a touch-screencontroller 140. The touch-screen controller 140 is connected to thefirst and second transparent electrodes 130, 132 through electrical bussconnections 136 and wires 134 and controls the touch screen 120. Thetouch-screen controller 140 detects touches on the touch screen 120 bysequentially electrically energizing and testing the x-dimension firstand y-dimension second transparent electrodes 130, 132.

U.S. Patent Application Publication No. 2011/0291966 discloses an arrayof diamond-shaped micro-wire structures. In this disclosure, a firstelectrode includes a plurality of first conductor lines inclined at apredetermined angle in clockwise and counterclockwise directions withrespect to a first direction and provided at a predetermined interval toform a grid-shaped pattern. A second electrode includes a plurality ofsecond conductor lines, inclined at the predetermined angle in clockwiseand counterclockwise directions with respect to a second direction, thesecond direction perpendicular to the first direction and provided atthe predetermined interval to form a grid-shaped pattern. Thisarrangement is used to inhibit Moiré patterns. The electrodes are usedin a touch screen device. Referring to FIG. 17, this prior-art designincludes micro-wires 150 arranged in a micro-pattern 156 with themicro-wires 150 oriented at an angle to the direction of horizontalfirst transparent electrodes 130 and vertical second transparentelectrodes 132. The horizontal first transparent electrodes 130 areformed on an opposite side of a transparent substrate from the verticalsecond transparent electrodes 132.

The structure of FIG. 16 has first and second transparent substrates122, 126 and a dielectric layer 124. In some applications, it is usefulto form both horizontal and vertical first and second transparentelectrodes 130, 132 on the same side of a single transparent substrateto reduce the thickness of the structure.

In such an application however, if the first and second transparentelectrodes 130, 132 include impressed micro-wires formed in a layercoated over the single transparent substrate, it is difficult toelectrically connect the micro-wires 150 (FIG. 17) to wires 134 (FIG.16) external to the single transparent substrate.

SUMMARY OF THE INVENTION

There is a need, therefore, for alternative substrate and multi-layermicro-wire structures that provide reduced thickness and electricalconnections for transparent electrodes having micro-wires in animprinted micro-wire micro-pattern.

In accordance with the present invention, a multi-layer micro-wirestructure, comprises:

a substrate having a substrate edge;

a first layer formed over the substrate extending to a first layer edge;

one or more first micro-channels imprinted in the first layer, at leastone imprinted first micro-channel having a micro-wire forming at least aportion of an exposed first connection pad in the first layer;

a second layer formed over the first layer extending to a second layeredge;

one or more second micro-channels imprinted in the second layer, atleast one imprinted second micro-channel having a micro-wire forming atleast a portion of an exposed second connection pad in the second layer;

wherein the second-layer edge is farther from the substrate edge thanthe first-layer edge for at least a portion of the second-layer edge sothat the first connection pads are exposed through the second layer.

The present invention provides a multi-layer micro-wire structure withreduced thickness and improved electrical connectivity.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent when taken in conjunction with the followingdescription and drawings wherein identical reference numerals have beenused to designate identical features that are common to the figures, andwherein:

FIG. 1 is a perspective of a multi-layer micro-wire structure accordingto an embodiment of the present invention;

FIG. 2 is a cross section of a multi-layer micro-wire structureaccording to an embodiment of the present invention corresponding toFIG. 1;

FIG. 3 is a plan view of a micro-wire micro-pattern useful inembodiments of the present invention;

FIG. 4A is a perspective of a micro-channel formed in a layer on asubstrate useful in embodiments of the present invention;

FIG. 4B is a perspective of a micro-wire in a micro-channel formed in alayer on a substrate useful in embodiments of the present invention;

FIGS. 5A and 5B are perspectives of an embodiment of the presentinvention;

FIGS. 6-10 are perspectives of various embodiments of the presentinvention;

FIG. 11 is a perspective of an embodiment of the present inventionhaving overlapping, orthogonal electrodes;

FIGS. 12A-12D are cross sections of embodiments of the present inventionhaving a connector;

FIG. 13 is a perspective of another embodiment of the present invention;

FIG. 14 is a flow diagram illustrating a method according to anembodiment of the present invention;

FIG. 15 is a perspective of an imprinted structure useful in forming anembodiment of the present invention; and

FIG. 16 is a perspective of a touch screen and a display according tothe prior art; and

FIG. 17 is a plan view of micro-wire electrodes according to the priorart.

The Figures are not drawn to scale since the variation in size ofvarious elements in the Figures is too great to permit depiction toscale.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed toward multiple layers of electricallyconductive micro-wires formed in micro-channels over a substrate. Thelayer structures facilitate electrical connections between themicro-wires and electronic components external to the substrate on whichthe multi-layer micro-wire structures are formed, providing improvedconnectivity and manufacturability.

Referring to the perspective of FIG. 1 and cross section of FIG. 2 in anembodiment of the present invention, a multi-layer micro-wire structure5 includes a substrate 10 having a substrate edge 12. A first layer 20is formed over the substrate 10 and extends to a first layer edge 22. Asecond layer 30 is formed over the first layer 20 and extends to asecond-layer edge 32. As shown in FIG. 2, one or more firstmicro-channels 62 are imprinted in the first layer 20. At least oneimprinted first micro-channel 62 has a micro-wire 50 forming at least aportion of an exposed first connection pad 24 in the first layer 20. Atleast one second micro-channel 64 is imprinted in the second layer 30.At least one imprinted second micro-channel 64 has a micro-wire 50forming at least a portion of an exposed second connection pad 34 in thesecond layer 30. The first-layer edge 22 is a distance D1 from thesubstrate edge 12. The second-layer edge 32 is a distance D2 from thesubstrate edge 12. D2 is greater than D1 for at least a portion of thesecond-layer edge 32 so that the first connection pads 24 are exposedthrough the second layer 30.

In an embodiment, the first connection pads 24 are electricallyconnected to electrical busses 54 or micro-wire electrodes 52 (FIG. 1).Likewise, the second connection pads 34 are electrically connected toelectrical busses 54 or micro-wire electrodes 52. In other embodiments,referring also to FIG. 3, a micro-pattern 56 of micro-wires 50 areelectrically interconnected to form apparently transparent first orsecond connection pads 24, 34, micro-wire electrodes 52, or electricalbusses 54. The micro-patterns 56 are the same or different for the firstor second connection pads 24, 34, micro-wire electrodes 52, orelectrical busses 54. In at least one embodiment, the micro-patterns 56of the micro-wires 50 used for first or second connection pads 24, 34,or electrical busses 54 have a higher spatial density than themicro-patterns 56 of the micro-wires 50 used for the micro-wireelectrodes 52. In other embodiments, the first or second connection pads24, 34, or electrical busses 54 have wider micro-wires than themicro-wire electrodes 52 or have filled areas of conductive material. Inan embodiment, the first or second connection pad 24, 34 is a singlemicro-wire and the first or second connection pad 24, 34 is a solidelectrical conductor.

Referring to FIG. 4A, the first layer 20 is formed over the substrate 10and a micro-channel 60 is imprinted in the first layer 20. Referring toFIG. 4B, the micro-channel 60 is filled with a micro-wire 50 in thefirst layer 20 on the substrate 10. Similarly, micro-wires 50 are formedin micro-channels 60 imprinted in the second layer 30 (not shown). Sincethe micro-wires 50 can fill the micro-channels 60, it can be difficultto distinguish them in the Figures. Micro-channels 60 are thereforeindicated with and arrow and the micro-wires 50 are indicated with leadlines.

As shown in the embodiment of FIG. 1, the first connection pads 24 arearranged in a common row adjacent to the substrate edge 12. By adjacentis meant that no other connection pads are between the first connectionpads 24 and the substrate edge 12. The second connection pads 34 arealso in a common row adjacent to the first connection pads 24 on a sideof the first connection pads 24 opposite the substrate edge 12 so thatthe first connection pads 24 are between the substrate edge 12 and thesecond connection pads 34.

In an embodiment, as illustrated in FIG. 1, the first layer 20 has astraight edge or the second layer 30 has a straight edge. In analternative embodiment of the multi-layer micro-wire structure 5,referring to FIGS. 5A and 5B, both the first and second connection pads24, 34 in first and second layers 20, 30 are arranged adjacent to thesubstrate edge 12 of the substrate 10. First layer 20 has a straightfirst-layer edge 22 coincident with the substrate edge 12. As shown inFIG. 5A, the second layer 30 has a crenellated second-layer edge 32 andthe first connection pads 24 alternate in a row with the secondconnection pads 34 along the substrate edge 12. Micro-wires 50 areelectrically connected to the first and second connection pads 24, 34.FIG. 5B is a detail of the crenellated second layer edge 32 andillustrates the structure of the crenellated second-layer edge 32 andthe micro-wire 50 connections to the first connection pads 24 withdashed hidden lines. Referring to FIG. 6, both the first and secondconnection pads 24, 34 connected to micro-wires 50 in the correspondingfirst and second layers 20, 30 are arranged adjacent to the substrateedge 12 of the substrate 10 in a row but do not alternate. Instead, thefirst connection pads 24 are at one end of the row and the secondconnection pads 34 are at the other end of the row. The first-layer edge22 is coincident with the substrate edge 12 and the second-layer edge 32is coincident with the substrate edge 12 for only a portion of thesubstrate edge 12.

In the embodiment of FIG. 1, the first connection pads 24 form a firstrow and the second connection pads 34 form a second, different row. Thefirst connection pads 24 and the second connection pads 34 are alignedso that the corresponding first connection pads 24 and second connectionpads 34 form a line orthogonal to the substrate edge 12. In analternative embodiment illustrated in FIG. 7, the first connection pads24 on the first layer 20 form a first row adjacent to the first-layeredge 22 and the second connection pads 34 on the second layer 30 form asecond, different row adjacent to the second-layer edge 32 but the firstconnection pads 24 and the second connection pads 34 are offset so thatthe first connection pads 24 and the second connection pads 34 alternatealong the substrate edge 12 of the substrate 10 and the correspondingfirst and second connection pads 24, 34 do not form a line orthogonal tothe substrate edge 12.

In the embodiments of FIGS. 5A, 6, and 7, the first-layer edge 22 iscoincident with the substrate edge 12. In an alternative embodiment,illustrated in FIGS. 1 and 8, the first-layer edge 22 is not coincidentwith the substrate edge 12. Furthermore, in the embodiments of FIG. 5Aand 6, a portion of the second-layer edge 32 is coincident with thefirst-layer edge 22. Alternatively, as shown in FIGS. 1 and 7, none ofthe second-layer edge 32 is coincident with the first-layer edge 22.Referring to FIG. 8, the first-layer edge 22 of the first layer 20 isnot coincident with the substrate edge 12 of the substrate 10 and thesecond-layer edge 32 of the second layer 30 is only partially coincidentwith the first-layer edge 22. Referring to FIG. 9, the first-layer edge22 of the first layer 20 is coincident with the substrate edge 12 of thesubstrate 10 and the second-layer edge 32 of the second layer 30 is onlypartially coincident with the first-layer edge 22. In FIGS. 8 and 9, thefirst and second connection pads 24, 34 alternate in a single row.

Referring to FIG. 10 in yet another embodiment of the present invention,the substrate 10 has a second substrate edge 13 extending in a differentdirection from the substrate edge 12. The first connection pads 24 arearranged in a row adjacent to the substrate edge 12 and the secondconnection pads 34 are arranged in a row adjacent to the secondsubstrate edge 13. In such an embodiment, a portion of the second-layeredge 32 of second layer 30 extends parallel to the substrate edge 12 andanother portion of the second-layer edge 32 of the second layer 30extends parallel to the second substrate edge 13. The first layer 20 andthe first-layer edge 22 are shown as coincident with the substrate edge12 and the second substrate edge 13 but can be inset from either of thesubstrate edge 12 or the second substrate edge 13 (not shown).

The first and second connection pads 24, 34 arrangements and the firstand second layer 20, 30 structures are useful in connecting externalcontrol devices to an arrangement of micro-wire electrical busses 54, asshown in the multi-layer micro-wire structure 5 of FIG. 11. As shown inFIG. 11, the first and second layers 20, 30 are formed on the substrate10. The first connection pads 24 are formed along the first-layer edge22 coincident with the substrate edge 12. The second connection pads 34are formed along the crenellated second-layer edge 32 forming a singlerow of connection pads. The micro-wire electrical busses 54 areconnected to horizontal micro-wire electrodes 52A over the first layer20 under the second layer 30 and the micro-wire electrical busses 54 areconnected to vertical micro-wire electrodes 52B over the second layer30. The horizontal micro-wire electrodes 52A extend in a directionorthogonal to the vertical micro-wire electrodes 52B. Where thehorizontal micro-wire electrodes 52A and the vertical micro-wireelectrodes 52B overlap or are closely adjacent, capacitors are formedthat are useful in a capacitive touch screen. In other embodiments ofthe present invention, busses corresponding to the micro-wire electricalbusses 54 and electrodes corresponding to the horizontal and verticalmicro-wire electrodes 52A, 52B include transparent conductors and do notnecessarily include micro-wires 50. The present invention includes suchembodiments. In other embodiments, the micro-wires 50 and the first andsecond connection pads 24, 34 of the present invention are used toprovide external electrical connections to various electrical circuitsand arrangements of electrical conductors.

The various edge structures and the first and second connection pad 24,34 arrangements illustrated are useful for enabling various electricalinterconnections with electrical cables external to the substrate 10 andstructures formed thereon. In embodiments having first and secondconnection pads 24, 34 arranged in a single row, a single row ofconnection points in, for example, a ribbon cable is affixed to thefirst and second connection pads 24, 34 (e.g. as in FIGS. 6, 8, and 9).In embodiments having the first and second connection pads 24, 34arranged in separate rows, a double row of connection wires are affixedto the first and second connection pads 24, 34 (e.g. as in FIGS. 1 and7). In embodiments having the first and second connection pads 24, 34arranged along separate substrate edges, separate cables areelectrically connected to the separate rows of first and secondconnection pads 24, 34 (e.g. as in FIG. 10).

Referring to FIGS. 12A, 12B, 12C, and 12D, cross sections of embodimentsof the present invention corresponding to FIG. 7 illustrate thesubstrate 10 with the first and second layers 20, 30 having thesubstrate edge 12, first-layer edge 22, and second-layer edge 32. Thefirst connection pad 24 is formed on the first layer 20 and the secondconnection pad 34 is formed on the second layer 30. As shown in FIGS.12B, 12C, and 12D, an electrical connector 70, for example, a ribboncable, including multiple first and second wires 74, 76 is electricallyconnected to the first and second connection pads 24, 34 with anelectrically conductive material, for example by using solder, adhesiveconductors, or anisotropic conductors. At least one first wire 74 iselectrically connected to one of the first connection pads 24 and atleast one second wire 76 is electrically connected to one of the secondconnection pads 34.

In FIG. 12B, the electrical connector 70 is a compliant, compressible,or flexible electrical connector 70 that touches both the firstconnection pad 24 on first layer 20 and the second connection pad 34 onthe second layer. Referring to FIG. 12C, the electrical connector 70 isnot necessarily compliant, compressible, or flexible and can maintain arigid, flat surface. In such an arrangement the thickness T1 of anelectrically conductive material 72 between the first wire 74 of theelectrical connector 70 and the first connection pad 24 on the firstlayer 20 is greater than the thickness T2 of an electrically conductivematerial 72 between the second wire 76 of the electrical connector 70and the second connection pad 34 on the second layer 30. Thus, in anembodiment, the first wire 74 is electrically connected to the firstconnection pad 24 with an electrically conductive material having afirst thickness T1, the second wire 76 is electrically connected to thesecond connection pad 34 with the electrically conductive materialhaving a second thickness T2, and the first thickness T1 is greater thanthe second thickness T2. In FIG. 12D, the electrical connector 70 is notnecessarily compliant, compressible, or flexible and can maintain arigid, flat surface but the first and second layers 20, 30, or thesubstrate 10 are flexible, compressible, or compliant and are deformedto align the first connection pad 24 and the second connection pad 34with the first and second wires 74, 76 of the electrical connector 70.The various arrangements of the electrical connector 70 illustrated inFIGS. 12B-12D can be used with the various first and second connectionpads 24, 34 and the first and second layer 20, 30 structures illustratedin the Figures to connect external electrical components to electricalstructures formed over the substrate 10.

In another embodiment of the present invention and as illustrated inFIG. 13, the multi-layer micro-wire structure 5 further includes a thirdlayer 40 extending to a third-layer edge 42 formed over the second layer30 and the first layer 20, the third layer 40 having imprintedmicro-wires 50 forming a plurality of exposed third connection pads 44.The third-layer edge 42 is farther from the substrate edge 12 than thefirst-layer or second-layer edge 22, 32 for at least a portion of thefirst-layer or second-layer edge 22, 32 to expose the first and secondconnection pads 24, 34. As illustrated in FIG. 13, the third-layer edge42 is a distance D3 from the substrate edge 12 that is greater than thedistance D2 that the second-layer edge 32 is from the substrate edge 12and the distance D1 that the first-layer edge 22 is from the substrateedge 12.

As shown in FIG. 13, the third layer edge 42 is farther from thesubstrate edge 12 than the first-layer and second-layer edges 22, 32. InFIG. 13, all of the third layer edge 42 is farther from the substrateedge 12 than all of the first- and second-layer edges 22, 32. In anotherembodiment (not shown), only a portion of the third layer edge 42 isfarther from the substrate edge 12 than at least a portion of the first-or second-layer edges 22, 32, for example with a crenellated edge.

According to another embodiment of the present invention illustrated inFIG. 14, a method of making a multi-layer micro-wire structure 5includes providing a substrate 10 having a substrate edge 12 in step200. A first layer 20 is formed over the substrate 10 extending to afirst layer edge 22 in step 205. One or more first micro-channels 62 areimprinted in the first layer 20 in step 210. In step 215, the one ormore first micro-channels 62 in the first layer 20 are cured. In step220, conductive ink is deposited in the first micro-channels 62 andcured (step 225) to form micro-wires 50 in at least one imprinted firstmicro-channel 62. The first micro-wire 50 forms at least a portion of anexposed first connection pad 24 in the first layer 20.

A second layer 30 is formed over the first layer 20 extending to asecond layer edge 32 in step 305. In step 310, one or more secondmicro-channels 64 are imprinted in the second layer 30 and cured in step315. In step 320, conductive ink is deposited in the secondmicro-channel 64 and cured (step 325) to form micro-wires 50 in at leastone imprinted second micro-channel 62. The second micro-wire 50 forms atleast a portion of an exposed second connection pad 34 in the secondlayer 30. The second-layer edge 32 is farther from the substrate edge 12than the first-layer edge 22 for at least a portion of the second-layeredge 22 so that the first connection pads 24 are exposed through thesecond layer 30.

In step 400, an electrical connector 70 is affixed and electricallyconnected to the first and second connection pads 24, 34.

According to various embodiments of the present invention, the first andsecond connection pads 24, 34 are formed in a common row or along thesubstrate edge 12. The first or second layers 20, 30 are formed withstraight edges; alternatively the second layer is formed with acrenellated edge. In an embodiment, the first connection pads 24 areformed in a row adjacent to the substrate edge 12 and the secondconnection pads 34 are formed in a row adjacent to the first connectionpads 24 so that the first connection pads 24 are between the substrateedge 12 and the second connection pads 34. In another embodiment, thefirst connection pads 24 are formed adjacent to each other and thesecond connection pads 34 are formed adjacent to each other or the firstand second connection pads 24, 34 are formed alternately in a row.

In various embodiments, the second connection pads 34 are formed inalignment with the first connection pads 24 or are formed offset fromthe first connection pads 24.

In other embodiments, the first-layer edge 22 is formed coincident withthe substrate edge 12 or is formed not in coincidence with the substrateedge 12. In an embodiment, a portion of the second-layer edge 22 isformed coincident with the substrate edge 12. Alternatively, thesubstrate 10 has a second substrate edge 13 extending in a differentdirection from the substrate edge 12, and the first connection pads 24are formed in a row adjacent to the substrate edge 12 and the secondconnection pads 34 are formed in a row adjacent to the second substrateedge 13.

In an embodiment of the present invention, an electrical connector 70including multiple first and second wires is provided. At least onefirst wire is electrically connected to one of the first connection pads24 and at least one second wire is electrically connected to one of thesecond connection pads 34. The electrical connector 70 can be a ribboncable or a flex connector. The electrical connector 70 can be flexible,compressible, or compliant. Alternatively or in addition, the substrate10, the first layer 20, or the second layer 30 is flexible, compliant,or compressible.

In a further embodiment, a first wire 74 is electrically connected to afirst connection pad 24 with an electrically conductive material havinga first thickness and a second wire 76 is electrically connected to asecond connection pad 34 with the electrically conductive materialhaving a second thickness. The first thickness is greater than thesecond thickness.

In an embodiment, a third layer 40 extending to a third layer edge 42 isformed over the second layer 30, micro-channels 60 are imprinted in thethird layer 40 and micro-wires 50 formed in the micro-channels 60 toform a plurality of exposed third connection pads 44 in the third layer40. The third-layer edge 42 is farther from the substrate edge 12 thanthe first- or second-layer edge 22, 32 for at least a portion of thefirst- or second-layer edge 22, 32 to expose the first and secondconnection pads 24, 34. In an embodiment, the third-layer edge 42 isfarther from the substrate edge 12 than the first-layer and second-layeredges 22, 32.

In one embodiment of the present invention, the second-layer edge 32 ofthe second layer 30 is defined with an imprinting stamp that is used ina common step to imprint micro-channels 60. In a further embodimentreferring to FIG. 15, the second layer 30 is imprinted in a first stepto expose the first connection pads 24 in first layer 20 on substrate 10through the second layer 30 while leaving material forming the secondlayer 30 with the second connection pads 34 at the substrate edge 12. Ina second step, the edges of the substrate 10 and second layer 30material is removed, for example by cutting or abrading the edges of thesubstrate 10 along cut lines 80 to form a new substrate edge 12, asillustrated in FIG. 7. Material is removed from at least one, two, orthree edges depending on the final structure. For example, material isremoved from three sides to form the structure of FIG. 7 and material isremoved only from one side to form the structure of FIG. 5A or FIG. 9.

The first or second layers 20, 30 useful in the present invention caninclude a cured polymer material with cross-linking agents that aresensitive to heat or radiation, for example infra-red, visible light, orultra-violet radiation. The polymer material can be a curable materialapplied in a liquid form that hardens when the cross-linking agents areactivated. When a molding device, such as an imprinting stamp having aninverse micro-channel structure is applied to liquid curable materialcoated on the substrate 10 and the cross-linking agents in the curablematerial are activated, the liquid curable material in first or secondlayers 20, 30 is hardened into a cured layer with imprintedmicro-channels 60. The liquid curable materials can include a surfactantto assist in controlling coating on the substrate 10. Materials, tools,and methods are known for imprinting coated liquid curable materials toform cured layers having micro-channels 60.

Curable inks useful in the present invention are known and can includeconductive inks having metal particles, for example electricallyconductive nano-particles. The electrically conductive nano-particlescan be metallic or have an electrically conductive shell. Theelectrically conductive nano-particles can be silver, can be a silveralloy, or can include silver or other metals, such as tin, tantalum,titanium, gold, copper, or aluminum, or alloys thereof. The metalparticles can be sintered to form a metallic electrical conductor. Curedinks can include light-absorbing materials such as carbon black, a dye,or a pigment.

Curable inks provided in a liquid form are deposited or located inmicro-channels 60. Once deposited, the conductive inks are cured, forexample by heating or exposure to radiation such as infra-red, visiblelight, or ultra-violet radiation. The curing process drives out theliquid carrier and sinters the metal particles to form a metallicelectrical conductor. The curable ink hardens to form the cured ink thatmakes up micro-wires 50. For example, a curable conductive ink withconductive nano-particles is located by coating first or second layers20, 30 to fill micro-channels 60 and heated to agglomerate or sinter thenano-particles, thereby forming electrically conductive micro-wires 50.Materials, tools, and methods are known for coating liquid curable inksto form micro-wires 50 in micro-channels 60.

In an embodiment, a curable ink can include conductive nano-particles ina liquid carrier (for example an aqueous solution including surfactantsthat reduce flocculation of metal particles, humectants, thickeners,adhesives or other active chemicals). The liquid carrier is located inmicro-channels 60 and heated or dried to remove liquid carrier ortreated with hydrochloric acid, leaving a porous assemblage ofconductive particles that are agglomerated or sintered to form a porouselectrical conductor in a layer. Thus, in an embodiment, curable inksare processed to change their material compositions, for exampleconductive particles in a liquid carrier are not electrically conductivebut after processing form an assemblage that is electrically conductive.

Conductive inks are known in the art and are commercially available. Inany of these cases, conductive inks or other conducting materials areconductive after they are cured and any needed processing completed.Deposited materials are not necessarily electrically conductive beforepatterning or before curing. As used herein, a conductive ink is amaterial that is electrically conductive after any final processing iscompleted and the conductive ink is not necessarily conductive at anyother point in micro-wire 50 formation process.

According to various embodiments of the present invention, the substrate10 is any material having a surface on which a cured first layer 20 isformed. Substrate 10 can be a rigid or a flexible substrate made of, forexample, a glass, metal, plastic, or polymer material, can betransparent, and can have opposing substantially parallel and extensivesurfaces. Substrates 10 can include a dielectric material useful forcapacitive touch screens and can have a wide variety of thicknesses, forexample 10 microns, 50 microns, 100 microns, 1 mm, or more. In variousembodiments of the present invention, substrates 10 are provided as aseparate structure or are coated on another underlying substrate, forexample by coating a polymer substrate layer on an underlying glasssubstrate.

Substrate 10 can be an element of other devices, for example the coveror substrate of a display or a substrate, cover, or dielectric layer ofa touch screen. In an embodiment, a substrate 10 of the presentinvention is large enough for a user to directly interact therewith, forexample using an implement such as a stylus or using a finger or hand.Methods are known in the art for providing suitable surfaces on which tocoat a single curable layer. In a useful embodiment, substrate 10 issubstantially transparent, for example having a transparency of greaterthan 90%, 80% 70% or 50% in the visible range of electromagneticradiation.

A micro-channel 60 is a groove, trench, or channel formed on or insubstrate 10 and can have a cross-sectional width less than 20 microns,for example 10 microns, 5 microns, 4 microns, 3 microns, 2 microns, 1micron, or 0.5 microns, or less. Micro-channels 60 can have arectangular cross section, as shown. Other cross-sectional shapes, forexample trapezoids, are known and are included in the present invention.The width or depth of a layer is measured in cross section.

In various embodiments of the present invention, micro-channel 60 ormicro-wire 50 has a width less than or equal to 10 microns, 5 microns, 4microns, 3 microns, 2 microns, or 1 micron. In an example andnon-limiting embodiment of the present invention, each micro-wire 50 isfrom 10 to 15 microns wide, from 5 to 10 microns wide, or from 5 micronsto one micron wide. In some embodiments, micro-wire 50 can fillmicro-channel 60; in other embodiments micro-wire 50 does not fillmicro-channel 60. In an embodiment, micro-wire 50 is solid; in anotherembodiment micro-wire 50 is porous.

Electrically conductive micro-wires 50 and methods of the presentinvention are useful for making electrical conductors and busses fortransparent micro-wire electrodes and electrical conductors in general,for example as used in electrical busses 54. A variety of micro-patterns56 can be used and the present invention is not limited to any onepattern. Micro-wires 50 can be spaced apart, form separate electricalconductors, or intersect to form a mesh electrical conductor on or insubstrate 10 or first or second layers 20, 30. Micro-channels 60 can beidentical or have different sizes, aspect ratios, or shapes. Similarly,micro-wires 50 can be identical or have different sizes, aspect ratios,or shapes. Micro-wires 50 can be straight or curved.

Micro-wires 50 can be metal, for example silver, gold, aluminum, nickel,tungsten, titanium, tin, or copper or various metal alloys including,for example silver, gold, aluminum, nickel, tungsten, titanium, tin, orcopper. Micro-wires 50 can include a thin metal layer composed of highlyconductive metals such as gold, silver, copper, or aluminum. Otherconductive metals or materials can be used. Alternatively, micro-wires50 can include cured or sintered metal particles such as nickel,tungsten, silver, gold, titanium, or tin or alloys such as nickel,tungsten, silver, gold, titanium, or tin. Conductive inks can be used toform micro-wires 50 with pattern-wise deposition or pattern-wiseformation followed by curing steps. Other materials or methods forforming micro-wires 50, such as curable ink powders including metallicnano-particles, can be employed and are included in the presentinvention.

Electrically conductive micro-wires 50 of the present invention can beoperated by electrically connecting micro-wires 50 through first orsecond connection pads 24, 34 and electrical connectors 70 to electricalcircuits that provide electrical current to micro-wires 50 and cancontrol the electrical behavior of micro-wires 50. Electricallyconductive micro-wires 50 of the present invention are useful, forexample in touch screens such as projected-capacitive touch screens thatuse transparent micro-wire electrodes and in displays. Electricallyconductive micro-wires 50 can be located in areas other than displayareas, for example in the perimeter of the display area of a touchscreen, where the display area is the area through which a user views adisplay.

Methods and devices for forming and providing substrates and coatingsubstrates are known in the photo-lithographic arts. Likewise, tools forlaying out electrodes, conductive traces, and connectors are known inthe electronics industry as are methods for manufacturing suchelectronic system elements. Hardware controllers for controlling touchscreens and displays and software for managing display and touch screensystems are well known. These tools and methods can be usefully employedto design, implement, construct, and operate the present invention.Methods, tools, and devices for operating capacitive touch screens canbe used with the present invention.

The present invention is useful in a wide variety of electronic devices.Such devices can include, for example, photovoltaic devices, OLEDdisplays and lighting, LCD displays, plasma displays, inorganic LEDdisplays and lighting, electrophoretic displays, electrowettingdisplays, dimming mirrors, smart windows, transparent radio antennae,transparent heaters and other touch screen devices such as resistivetouch screen devices.

The invention has been described in detail with particular reference tocertain embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

PARTS LIST

-   D1 distance-   D2 distance-   D3 distance-   T1 thickness-   T2 thickness-   x x dimension-   y y dimension-   5 multi-layer micro-wire structure-   10 substrate-   12 substrate edge-   13 second substrate edge-   20 first layer-   22 first-layer edge-   24 first connection pad-   30 second layer-   32 second-layer edge-   34 second connection pad-   40 third layer-   42 third-layer edge-   44 third connection pad-   50 micro-wire-   52 micro-wire electrode-   52A horizontal micro-wire electrode-   52B vertical micro-wire electrode-   54 electrical buss-   56 micro-pattern-   60 micro-channel-   62 first micro-channel-   64 second micro-channel-   70 electrical connector-   72 electrically conductive material-   74 first wire-   76 second wire-   80 cut lines-   100 display system and touch screen-   110 display-   120 touch screen-   122 first transparent substrate-   124 transparent dielectric layer-   126 second transparent substrate-   128 first pad area-   129 second pad area-   130 first transparent electrode-   132 second transparent electrode-   134 wires-   136 electrical buss connections-   140 touch-screen controller-   142 display controller-   150 micro-wire-   156 micro-pattern-   200 provide substrate step-   205 form first layer step-   210 imprint first-layer micro-channels step-   215 cure first-layer micro-channels step-   220 deposit conductive ink in first-layer micro-channels step-   225 cure conductive ink in first-layer micro-channels step-   305 form second layer step-   310 imprint second-layer micro-channels step-   315 cure second-layer micro-channels step-   320 deposit conductive ink in second-layer micro-channels step-   325 cure conductive ink in second-layer micro-channels step-   400 affix connector step

1. A multi-layer micro-wire structure, comprising: a substrate having asubstrate edge; a first layer formed over the substrate extending to afirst layer edge; one or more first micro-channels imprinted in thefirst layer, at least one imprinted first micro-channel having amicro-wire forming at least a portion of an exposed first connection padin the first layer; a second layer formed over the first layer extendingto a second layer edge; one or more second micro-channels imprinted inthe second layer, at least one imprinted second micro-channel having amicro-wire forming at least a portion of an exposed second connectionpad in the second layer; and wherein the second-layer edge is fartherfrom the substrate edge than the first-layer edge for at least a portionof the second-layer edge so that the first connection pads are exposedthrough the second layer.
 2. The multi-layer micro-wire structure ofclaim 1, wherein the first and second connection pads are arranged in acommon row.
 3. The multi-layer micro-wire structure of claim 1, whereinthe first and second connection pads are arranged along the substrateedge.
 4. The multi-layer micro-wire structure of claim 1, wherein thesecond layer has a crenellated edge.
 5. The multi-layer micro-wirestructure of claim 1, wherein the second layer has a straight edge. 6.The multi-layer micro-wire structure of claim 1, wherein the firstconnection pads are arranged in a row adjacent to the substrate edge,the second connection pads are arranged in a row adjacent to the firstconnection pads, and the first connection pads are between the substrateedge and the second connection pads.
 7. The multi-layer micro-wirestructure of claim 1, wherein the substrate has a second substrate edgeextending in a different direction from the substrate edge, the firstconnection pads are arranged in a row adjacent to the substrate edge,and the second connection pads are arranged in a row adjacent to thesecond substrate edge.
 8. The multi-layer micro-wire structure of claim1, wherein the first connection pads are adjacent to each other and thesecond connection pads are adjacent to each other.
 9. The multi-layermicro-wire structure of claim 1, wherein the first and second connectionpads alternate in a row.
 10. The multi-layer micro-wire structure ofclaim 1, wherein the first connection pads are aligned with the secondconnection pads.
 11. The multi-layer micro-wire structure of claim 1,wherein the first connection pads are offset from the second connectionpads.
 12. The multi-layer micro-wire structure of claim 1, wherein thefirst layer edge is coincident with the substrate edge.
 13. Themulti-layer micro-wire structure of claim 1, wherein a portion of thesecond layer edge is coincident with the substrate edge.
 14. Themulti-layer micro-wire structure of claim 1, further including aconnector including multiple first and second wires, at least one firstwire electrically connected to one of the first connection pads and atleast one second wire electrically connected to one of the secondconnection pads.
 15. The multi-layer micro-wire structure of claim 1,wherein the connector is a ribbon cable.
 16. The multi-layer micro-wirestructure of claim 1, wherein the connector is flexible, compressible,or compliant.
 17. The multi-layer micro-wire structure of claim 1,wherein the substrate, the first layer, or the second layer is flexible,compliant, or compressible.
 18. The multi-layer micro-wire structure ofclaim 1, wherein a first wire is electrically connected to a firstconnection pad with an electrically conductive material having a firstthickness, a second wire is electrically connected to a secondconnection pad with the electrically conductive material having a secondthickness, and the first thickness is greater than the second thickness.19. The multi-layer micro-wire structure of claim 1, further including athird layer extending to a third-layer edge formed over the secondlayer, the third layer having imprinted micro-channels includingmicro-wires forming a plurality of exposed third connection pads;wherein the third-layer edge is farther from the substrate edge than thefirst- or second-layer edge for at least a portion of the first- orsecond-layer edge to expose the first and second connection pads. 20.The multi-layer micro-wire structure of claim 19, wherein thethird-layer edge is farther from the substrate edge than the first- andsecond-layer edge.